This project is directed toward an understanding of the process of mating in Saccharomyces cerevisiae, and specifically the role of peptide mating factors. Mutants that are unable to make normal levels of mating factors are isolated and analyzed genetically, physiologically, and biochemically. Cell-volume analysis is used as a tool to monitor changes in cell-volume that accompany the response of cells to the mating factor produced by the opposite mating type. Mutants with potentially altered forms of the alpha mating factor are of particular interest. The mating factors from such mutants are being purified to determine the exact nature of their alterations.